Spectral and time-resolved photoluminescence studies of Eu-doped GaN Available to Purchase

We report on spectral and time-resolved photoluminescence (PL) studies performed on Eu-doped GaN prepared by solid-source molecular-beam epitaxy. Using above-gap excitation, the integrated PL intensity of the main $Eu3+$ line at 622.3 nm $(5D0→7F2$ transition) decreased by nearly 90% between 14 K and room temperature. Using below-gap excitation, the integrated intensity of this line decreased by only $∼50%$ for the same temperature range. In addition, the $Eu3+$ PL spectrum and decay dynamics changed significantly compared to above-gap excitation. These results suggest the existence of different $Eu3+$ centers with distinct optical properties. Photoluminescence excitation measurements revealed resonant intra-$4f$ absorption lines of $Eu3+$ ions, as well as a broad excitation band centered at $∼400 nm.$ This broad excitation band overlaps higher lying intra-$4f$ $Eu3+$ energy levels, providing an efficient pathway for carrier-mediated excitation of $Eu3+$ ions in GaN.